ABOVE-AVERAGE JOE: New Net Joe Johnson tries to drive around the Sixers’ Royal Ivey last night in Brooklyn’s 108-105 win in overtime in the preseason opener in Atlantic City. Photo: AP

ATLANTIC CITY, N.J. — The Nets took the floor for the first time this preseason last night with a roster full of players who have spent just a short time together.

But the Nets, and particularly the starting five, looked nothing like a team still trying to get used to playing with one another in a 108-105 victory over the Sixers at Boardwalk Hall.

Playing against a Philadelphia team without its best player, center Andrew Bynum, the Nets’ starters did what they were supposed to do. They easily outpaced their Sixers counterparts in the first and third quarters, outscoring them by a combined 58-34. Four starters — Deron Williams, Brook Lopez, Gerald Wallace and Joe Johnson — finished in double figures as the Nets looked cohesive on offense and forced the Sixers into plenty of mistakes on defense.

“It felt great,” said Johnson, who finished with 13 points and three assists. “We have so many mismatches on the court, with Deron being a big point guard, as well as me and Gerald. … We have a lot of guys who can post up and make plays, and tonight the ball moved great, and it didn’t stick.

“It was great to kind of get out there and get up and down the court and get into the flow.”

It was Lopez’s first live game action since he suffered his second foot injury of last season on March 4. After a sluggish start, he came on strong, finishing with a team-high 19 points on 6-of-11 shooting, including a perfect 7-for-7 from the foul line.

More importantly, he finished with team highs of nine rebounds and three blocked shots. The Nets are expecting Lopez to become more of a force at the defensive end this season.

“It’s just about being focused on it,” Lopez said. “It’s not about the numbers. If I give the same effort night in and night out, I’ll be fine.”

Brooklyn’s backcourt never got a chance to get in much of a rhythm thanks to Johnson spending much of the game in foul trouble. Johnson only was able to play a little more than eight minutes in the first half after picking up three quick fouls.

Nevertheless, Johnson and Williams were able to get some time together on the court, and showed flashes of their potential. They effectively paired up on some pick-and-rolls, and Williams found Johnson multiple times for open 3-pointers.

“It was good,” said Williams, who finished with 14 points, four rebounds and six assists. “I told you I was excited about the trade. … It was a big reason why I stayed, because of having him on board. I’ve been a big fan of his game.”

The Nets led by 18 early in the fourth quarter before the Sixers launched a comeback behind hot shooting from guard Nick Young. After Damien Wilkins tied the game with a pair of free throws with 45 seconds left, C.J. Watson came up short on a pair of opportunities to win the game in regulation.

In overtime, Andray Blatche hit the game-winning 15-foot jumper with 26.8 seconds remaining to put the Nets ahead, 106-105, and secured a crucial defensive rebound when Young’s jumper rimmed out with 10 seconds to go to ice the game.

It was a positive debut for a new-look franchise with high hopes for its first season in Brooklyn, where they’ll debut at their new home, Barclays Center, tomorrow night against the Wizards.

“I thought it was important for us to get a win in our first game as the Brooklyn Nets,” coach Avery Johnson said, “even though it’s preseason. It was important, and hopefully we’ll carry it over to the Barclays Center.”